1. Field of the Invention
The present invention relates to a mobile audio system capable of being detachably mounted in a vehicle and more particularly to such a system which is easily portable and capable of utilizing a connector having fewer contacts and the contacts all have the same signed carrying capacity.
2. Description of the Related Art
In order to prevent expensive high-performance mobile audio systems such as car radios, car stereo sets and others from being stolen, it has been proposed that they can be demountable and portable. Such proposals are disclosed, for example, in Japanese Laid-Open Utility Model Application Nos. 63-82654, 59-145088 and 59-40152. Furthermore, various structures for easily demounting mobile audio systems are disclosed, for example, in Japanese Laid-Open Utility Model Application Nos. 63-95280, 62-157189, 62-23749, 60-111084, 60-96889 and 60-94885. In addition, Japanese Laid-Open Utility Model Application 57-129202 discloses a mobile audio system which can be detachably mounted in and electrically connected to a vehicle through a connector.
Such anti-steal type mobile audio systems require a separation unit which increases manufacturing costs. Mobile audio systems are frequency sold as expensive high-performance audio sets. Such high-class audio sets frequency include high-power amplifiers. The high-power amplifier increases the weight of the mobile audio set which makes it less portable.
Where a connector is used to provide an electrical connection between a high-performance mobile audio system and a vehicle, the high-performance mobile audio system to have a large number of contacts in the connector. The mobile audio system including its power amplifier also requires special contacts to carry the amplifier signal.
In a mobile audio system with a radio, there is a further problem in that when the input of an antenna, handling weak signals, is connected with the radio adjacent to contact means for transmitting stronger or larger output signals, interference may be created, such as spurious oscillations, or the like. In the prior art, the antenna input section was placed remote from the mobile audio system. Thus, the input and output contacts could not be united into a single connector. This also provided a limitation of layout in the circuitry within the audio system.
Normally, reliable contacts in the connector are plated with a noble metal since they are repeatedly used when the mobile audio system are repeatedly mounted and demounted in the vehicle. On the other hand, remotely placed antenna contact means are fitting contacts which increase the area of contact. If the increased area of contact is placed with a noble metal, manufacturing cost are necessarily increased. Most frequently used antenna contact means which are not plated with a noble metal have a reliability problem during repeated use.